BAGHDAD, Iraq (CNN) -- An al Qaeda in Iraq leader who was suspected of helping to plan a large scale attack against coalition forces "in the near future" was killed by a U.S. air strike south of Baghdad last week, the U.S. military said.

The military also said it captured "dozens of suspected extremists" connected to al Qaeda in an assault south of Baghdad on Saturday.

Muhammad Khalil Ibrahim, identified as the deputy military leader for the al Qaeda's network south of Baghdad, was killed along with two other terrorists in the air strike on their vehicle on Dec. 27, the military said.

Ibrahim was "a key planner in numerous attacks against Coalition forces operating in the Mahmudiyah area, and was also involved in the facilitation of foreign terrorists and weapons," the military said.

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The news release announcing the deaths said Ibrahim "and other senior al Qaeda members were allegedly planning to conduct a large-scale attack against Coalition forces in the near future."

On Saturday, the U.S. military and Iraqi Army launched an assault south of Baghdad in the Ubaydi farmland area, described by one U.S. soldier as a place where "people are either aligned with al Qaeda in Iraq or they've been killed or chased away."

More than 40 suspected extremists were captured, including 32 that were on the Iraqi Army's "most-wanted list," the military said.

Meanwhile, Iraqi security forces banned cars and trucks from the roads of Baquba and two other cities in the Diyala province Friday to protect caravans of pilgrims returning from the the hajj in Mecca, an Iraqi military spokesman said.

Several thousand Iraqis traveled to Saudi Arabia for the annual pilgrimage, many of them in convoys of cars, trucks and buses. Last year's return was marred by several attacks that claimed the lives of both Sunni and Shiite pilgrims.

The vehicle ban for Baquba, al Khalis and al Muqdadiya will run through Friday as Iraqi security forces escort the pilgrims into the cities, where many will be met at mosques by their families.

The hajj is the annual Muslim pilgrimage to Mecca, the holiest city in Islam, and adult Muslims are required to go on the pilgrimage at least once during their lives.

But the journey has its risks for people traveling through a country at war. Diyala, the province north and east of Baghdad, has become one of the most dangerous areas in Iraq in recent months with shootings and bombings. E-mail to a friend